Discharge nozzles for propulsive jets



March 29, 1960 p; ASHWQQD T 2,930,186

DISCHARGE NOZZLES FOR PROPULSIVE JETS Filed Nov. 25, 1955 v 3 Sheets-Sheet 1 PETER FREDERICK Ash'wooo GEORGE WILL/AM CROSSE Inve ntors Attorneys March 29, 1960 P. F. ASHWOOD ETAL 7 2,930,186

DISCHARGE NOZZLES FOR PROPULSIVE JETS Filed Nov. 25, 1955 3 Sheets-Sheet 2 FIG. 7.

P TER FREDERICK ASHWOOD E GEORGE WILL MM GROSSE Inventors March 29, 1960 Filed Nov. 25, 1955 P. F. ASHWOOD ET AL 2,930,186

DISCHARGE NOZZLES FOR PROPULSIVE JETS 3 Sheets-Sheet 3 FIG. 8

swan/rm PETER F. ASHWOOD GEORGE W CROSSE DISCHARGE N OZZLES FOR PROPULSIVE JETS Peter Frederick Ashwood, Farnham, and George William Crosse, Farnborough, England, assignors to Minister of Supply in Her Majestys Government of the United Kingdom of Great Britain and Northern Ireland, London, England Application November 25, 1955, Serial No. 549,107

Claims priority, application Great Britain November 26, 1954 9 Claims. (Cl. 60-356) The invention relates to discharge nozzles for. propulsive jets.

An object of the invention is to provide such a nozzle in which the structure defining the flow path for the propulsive fluid stream is movable to vary the configuration. One requirement is a nozzle which in one position defines a flow path of convergent divergent configuration.

Another object is to provide a nozzle wherein the flow path approaches a circular transverse section as is desirable for reasons of symmetry and reduction of periphery of the flow path.

The invention consists in a discharge nozzle for a propulsive fluid stream having at least one wall portion extending downstreamwardly of a duct for the fluid stream, supporting means for the wall portion and a pivot attachment between the latter and the supporting means whereby the wall portion is pivotable to vary the configuration of the nozzle about an axis extending transversely to the direction of fluid flow at a region upstream of the downstream end of the wall portion.

The invention further consists in a discharge nozzle for a propulsive fluid stream having a duct for the stream, spaced side walls extending downstreamwardly of the duct, opposed wall portions each extending downstreamwardly of the duct and between the side walls, supporting means for the wall portions, pivot attachments between each wall portion and the supporting means whereby each wall portion is pivotable to vary the configuration of the nozzle about an axis extending transversely to the direction offluid flow at a region upstream of the downstream end of the wall portion, and means for pivoting the wall portions simultaneously in opposite directions.

The provision of a wall portion movable in the way described between spaced side walls is of advantage in providing and maintaining a fluid seal during movement of the wall portion since a simple sliding motion over the side walls is involved. This advantage is mitigated however in that the side walls, being substantially flat, have a comparatively low resistance to distortion under fluid pressure.

Accordingly the invention further consists in that the nozzle is externally enveloped by a circumferentially continuous tension-resistant structure of generally circular form, the side walls being supported therefrom. The circular structure may be a tubular casing or an open structure.

' Although pivoting of the wall portion provides for variation in the nozzle configuration without necessarily changing the area of the flow path in the region of the pivot axis, it is nevertheless desirable to provide for a variation of the latter area.

Accordingly the invention further consists in that provision is made for moving the pivot attachment of the wallportion in the direction transverse to the fluid flow United Sttes Patent fc) and to the pivot axis sothat the'wall'portion is moved to vary the flow area of the nozzle. Where opposed wall portions are involved their pivot attachments are moved similarlyand simultaneously whereby the wall portions move towards or away from one another.

The foregoing and other features of the invention may be fully understood from the following description with reference to the accompanying drawings of alternative constructional embodiments of the invention.

In the drawings:

Fig. 1 is a sectional view of a nozzle structure accordi'ing to the invention taken along the direction of fluid Figs. 2 and ,3, are a section elevation and plan respectively of the same nozzle structure, Fig. 3 being taken in the direction of arrows IIIlll in Fig. 2.

Fig. 4 is an end elevation of the same nozzle structure in the direction of arrows IV-IV in Fig. 3.

Fig. 5 is an isometric view of a detail of the construction.

Figs. 6 and 7 are respectively side and end elevations partly sectioned of an alternative nozzle structure.

Fig. 8 shows an enlarged cut-away view of the eccentric arrangement used to alter the flow path of the nozzle. 7 V

Fig. 9 is an enlarged view of the sealing means employed in conjunction with the movable nozzle walls.

Referring to Figs. 1 to 5 the construction is applied to a discharge nozzle from a fluid duct 1 of circular section and constitutes the propulsive nozzle of, for example, a jet propelled aircraft- The circular duct 1 is enclosed in a radially spaced casing 2 which extends downstream of the duct 1 to the outlet plane of the nozzle. Two side walls 3 extend frorn'the downstream end of the duct, into which they merge, to the nozzle outlet 4. The side walls 3 lie, in any transverse section of the nozzle, substantially on parallel and opposite chords of the circular casing 2. Disposed symmetrically on opposite sides of a diametrical plane extending transversely to the side Walls are two movable nozzle wall portions 5. In transverse section each wall portion has a convex outward arcuate part extending between the side walls and flanges 6 extending from each edge of the arcuate part towards the diametrical plane, which flanges have sliding contact with the side walls 3. The longitudinal section is of convexinward curved form. The flanges 6 are thus of saddlelike shape and, when appropriately positioned, define with the side walls a nozzle of convergent-divergent configuration, the region of greatest convexity of the 1ongitudinal section corresponding approximately to the throat 7 of that configuration. At this throat region, which is nearer to the upstream than the downstream end of the nozzle, the two flanges of each wall portion constitute a trunnion mounting for the wall portion. Thus the two flanges carry coaxial spindles 8 extending outwardly therefrom, the spindle axes of the two wall .portions being parallel to the aforementioned diametrical plane and spaced equally on opposite sides of that plane. On each wall portion, the spindles 8 pass through the bores of each of the two eccentric bushings 9 which are rotatably mounted in the side walls. Thus, by virtue of the eccentricity of the bores of the two bushings, the spindle axis is transposed laterally when the bushings are rotated, with corresponding bodily movement of the wall portion. Each bushingcarries, outward of the side walls, an inte gral toothed wheel 10 which meshes with a correspondpas'ses outwardlyof one wall portion through holes 13 in the side walls. An intermediate point on the cross-bar is connected to a piston rod 14 of a piston'operatmg lll" 2, so that movement of the piston rotates the cranks and integral toothed wheels simultaneously and the enmeshed toothed wheels are likewise simultaneously rotated. The wheels are so arranged that the spindle axes of the respective walls portions are always parallel but move, upon rotation of the wheels, simultaneously towards or away from one another, the area of the nozzle in the plane of the spindle axes being correspondingly decreased or increased.

Each spindle 8 extends outwardly beyond the associated toothed wheel and carries fixed thereto a slotted arm 16 extending towards and through the diametrical plane. The two slotted arms on the spindles at the same side of the wall portions overlay one another, the slots 17 intersecting in the diametrical plane. Each one of a pair of hydraulic jacks 18 lying longitudinally of the nozzle in the diametrical plane outwardly of the respective side walls have a transversely extending actuating pin 19 which passes through the slots 17 at their intersection. The jacks 18 are attached to the casing 2. The operation of each jack 18 causes the slotted arms to rotate in unison about their respective spindle axes so as to pivot the wall portions symmetrically about these axes to vary, for example, the divergency of the nozzle outlet and the area of the discharge orifice. Such variations may proceed simultaneously with or independently of variation of the spacing of the spindle axes. The adjacent flanges 6 of the wall portions have their parts forward and rearward of the spindles 8 somewhat angled to one another to permit pivoting of the wall portions. At the downstream extremity of each wall portion the arcuate part thereof has the same curvature as the casing so that it may closely approach the latter. The curvature of the arcuate part is progressively increased however towards the plane of the pivot axes where it is greater than that of the duct, so affording an arc appreaching, as far as the trunnion mounting allows, a semi-circle.

To prevent leakage of the fluid outwardly of the wall portions the latter are each provided at the plane of the spindle axes with an integral part-spherical pad 20 externally embracing the arcuate part of the wall portion so as to extend circumferentially between the side walls. A continuation 21 of the fluid duct wall extends downstreamwardly between the side walls to the region of the pad 20 and is provided with a series of circumferentially consecutive fingers 22 inclined inwardly and upstreamwardly towards and in rubbing contact with the pad. The fingers 22 together form a part-circumferential fluid seal, being each provided with a circumferential extension 23 (shown in Fig. 5) overlapping an adjacent finger. The inclination of the fingers is such that the upstream fluid pressure tends to constrain them against the pad. At the same time the flexibility of the fingers enables them to accommodate bodily movement of the pad as well as pivoting movement. Additional fluid sealing means consists of a second part-circumferential series of fingers 24 arranged to bear on the upstream edge of the wall portion over the arcuate part thereof. The fingers have overlapping extensions 25 and are attached to the duct as before but in this case are inclined inwardly and downstreamwardly so as to be constrained by the internal fluid pressure outwardly against the wall portion. Thus the fingers also direct the fluid into the nozzle entry, while movement of the wall portions is again accommodated by the flexibility of the fingers. Sealing between the arcuate parts of each wall portion and the side walls is afforded, throughout the length of the nozzle, by the flanges 6 overlapping the .side wall, but a longitudinal channel accommodating a sealing pad could be provided. It will be noted that the internal fluid pressure on the concave outward section of the arcuate part tends to promote a sealing effect at the edges thereof.

Although for an understanding of the invention it is convenient to consider the side walls 3 to be equidistant along the nozzle, the distance between them at any longi tudinal region of the nozzle is varied in the described construction for the reason that the side walls effect an encroachment on the transverse area available in a truly circular nozzle which encroachment is desirably mitigated throughout the nozzle and particularly in the outlet plane. Thus while the side walls are parallel in the region of the spindle bushings 9, the distance between them is progressively increased towards the nozzle outlet. This lateral divergence of the side walls introduces a complication in that the edges of the arcuate parts of the wall portions are similarly divergent and do not move in the same plane upon pivoting of the portions. Consequently the side walls are not truly flat but are inclined very slightly inwardly between their intersections with the casing and diametrical plane respectively. Each side wall 3 is supported from the casing 2 by a plurality of longitudinally spaced 'ribs 26 which subdivide the cavity between the casing and side walls into successive fluid tight pockets each of which is in communication through an associated aperture 27 in the side wall with the fluid in the nozzle, so that the side wall is not subjected to pressure dilferentials, these being transferred to the casing.

In the alternative nozzle construction shown in Figs. 67 parts corresponding to those of the previous construction are correspondingly numbered. Thus the nozzle has a circular duct 1 for the fluid stream surrounded by a spaced casing 2, and spaced side walls 3 supported from the casing which side walls diverge from the up stream ends to the nozzle outlet 4. Two wall portions 5 are disposed symmetrically on either side of a diametrical plane along the axis of the duct and bisecting each side wall. The wall portions 5 have parts curved concave inwardly in transverse section and edge flanges 6 slidably engaging the side walls. The wall portions extend upstreamwardly from the nozzle outlet and terminute in the region of the upstream ends of the side walls. The transverse sections of the wall portions at their upstream ends are very nearly semi-circular. The curvature of each portion decreases progressively towards the downstream end where it approximates to the curvature of the casing 2 at the nozzle outlet. In longitudinal section the wall portions are straight. Each wall portion has transversely spaced external brackets 28 near its upstream end each bracket having a sleeve 29. Referring now to Fig. 8 it can be seen that each wall portion has a spindle 30 passing through the sleeves 29 and the wall portion is pivotable about the spindle axis which extends approximately tangentially to the semicircular section of the portion at its upstream end and parallel to the diametrical plane. Each spindle 30 has a pair of journal brackets 31 associated therewith attached to the casing. Each journal bracket 31 houses a rotatable bushing 32 having an eccentric recess 33, into which the adjacent end of the spindle loosely fits. Each bushing has attached to it and integral with it a pulley 34 so that upon simultaneous rotation of the pulley 34 at opposite ends of the spindle, the spindle axis is moved eccentrically while remaining parallel to the diametrical plane with corresponding movement of the wall portion. A transverse shaft 35 is provided at a region upstream of the spindles and is rotatably mounted on the casing 2 in trunnions 36. The shaft 35 is parallel to each spindle 30 and carries four pulleys 37. Uncrossed belts 38 pass from two of these pulleys 37 to the pulleys 34 associated with one wall portion and crossed belts 39 pass from the other two pulleys 37 to the pulleys 34 associated with the other wall portion. Thus the wall portions are moved simultaneously towards or away from one another upon rotation of the shaft 35 which is effected by the lever 40 attached thereto. In summary 1 finger of the pair.

sesame eccentrically. Meantime, about spindle 30 is a journal 7 29 which is attached by means of brackets 28 to wall portions 5. Thus the eccentric movement of spindle 3t) imparts, through 29 and 28, a corresponding movement to wall portions 5 causing them to pivot about spindles 41, the structure of which will be described hereinafter. To provide for pivoting of the wall portions about their respective spindle axes each portion has two laterally extending opposed second spindles 41 having a common axis remote from the spindle axis. Each of said second spindles is rotatable in a yoke 42 which is rigidly connected to piston rods 43 of paired pistons 44. The paired pistons 44 operate in a common cylinder block 45 which also houses the paired pistons 44 associated with second spindle 41 of the opposite wall portion. The common cylinder block is attached to a guide rod 46 which is slidable lengthwise in guide brackets 47 on the casing 2, the guide rod sliding in the diametrical plane of symmetry of the nozzle. Joint action of the pistons secured to each yoke causes the associated wall portion to pivot about the spindle 30 thereby producing a variation in the nozzle configuration. As eachwall portion pivots about its associated spindle 30, the second spindle 41 will also move about spindle 30 causing the cylinder block in rod 46 to slide in a downstream direction as the wall portion is opened and in an upstream direction as the wall portion is closed. Alternative connections 48, 49 to the cylinder blocks for operating fluid are formed in spirals to accommodate movement of the block. As each cylinder block slides fore and aft in response to movement of the wall portions, the spirals in the flexible connections 48 and 49 will contract or expand thereby permitting alternate lengthening or shortening of the connections. Fig. 9 shows an enlarged view of the means employed to obtain a reasonably good seal, and therefore provide a minimum of fluid leakage, between the stationary duct 1 and movable wall portions 5. It can be seen that duct 1 terminates in a downstream portion 50 of convergent form in the direction of flow and has a sealing lip 51 at its downstream end extending downstreamwardly of the upstream ends of the wall portions and side walls and internally thereof. The sealing lip has circumferentially successive axial fingers 52 each bearing on the nozzle walls. One finger of adjacent pairs has a circumferential extension 53 overlapping the other The fingers 52 yield to accommodate movement of the wall portions relatively to the duct 1 while fluid leakage between the fingers is opposed by the extensions 53. The arrangement is such that the wall portions are capable, in one position, of defining together with the convergent portion 50 of the duct a flow path of convergent-divergent configuration. The side walls 3 are supported on ribs 26 attached to the casing 2. As the pivot axes of the wall portions are disposed outwardly thereof, the distance between the side walls in any transverse section increases towards diametrical plane to permit pivoting the wall portions.

In each of the constructions described the operation of the pivoting means for the wall portions constituted in one case by the jacks 18 and in the other by the pistons and cylinders 44, 45 may be controlled in dependence upon for example the ratio of pressure of the fluid in the duct 1 and the ambient fluid pressure or the ambient flow Mach number relative to the propelled vehicle so that the nozzle becomes increasingly divergent as either quantity increases. The operation of the hydraulic cylinder 15 or-the lever 40 varying the position, of the spindle axes and hence the nozzle area is related to a fuel control of, for example, an afterburner upstream of the nozzle so that the area is increased as the fuel supply increases. 7

We claim:

1. A discharge nozzle for a propulsive fluid strea comprising a rigid duct for conducting the fluid stream said duct having upstream and downstream ends, a pair of spaced side walls extending downstreamwardly of said duct, a pair of oppositely disposed generally semi-circular rigid wall portions adjacent said side walls, said wall portions having side flanges positioned to cooperate with said side walls to form fluid seals, additional sealing means between the upstream ends of said wall portions and said duct, said sealing means being yieldable to accommodate relative movement between said wall portion and said duct supporting means for said side walls, means adjacent the downstream end of said duct pivotablymounting the upstream ends of said wall portions on said supporting means about an axis transverse to the fluid flow, means operatively connected to said mounting means for moving the same to a position in which the pivotal axes of said wall portions occupy a position parallel to the initial position of said axes, and means operatively connectedto said wall portions for rotating the wall portions about said pivotal axes whereby the flow area through said nozzle is varied.

2. A discharge nozzle for a propulsive fluid stream comprising a rigid duct for conducting the fluid stream, said duct having upstream and downstream ends, a pair of spaced side walls mounted downstreamwardly of said duct, a pair of oppositely disposed generally semi-circular rigid wall portions within said side walls,'said wall portions having side flanges positioned to cooperate with said side walls to form a fluid seal, spindles secured to said side flanges and protruding from opposite sides 3. The combination set forth in claim 2 and further 7 comprising sealing means between the upstream ends of said wall portions and said duct, said sealing means being yieldable to accommodate relative movement between said wall portion and said duct.

4. The combination set forth in claim 3 wherein said sealing means comprises a plurality of flexible fingers and circumferential extensions overlapping adjacent fingers.

5. A discharge nozzle for a propulsive fluid stream comprising a rigid duct for conducting the fluid stream, said duct having upstream and downstream ends, a pair of oppositely disposed generally semi-circular rigid wall portions adjacent the downstream end of said duct, a casing surrounding said duct and wall portions, sleeves secured to the upstream ends of said wall portions, first and second spindles passing through said sleeves and extending transversely to the fluid flow to pivotably mount said wall portions about said spindle axes adjacent the downstream end of said duct, journal brackets secured to said casing, a rotatable bushing in each bracket, an eccentric recess in each bushing for receiving an end of one of said spindles, means operatively connected to said bushings for rotating the same and moving said spindles to a position in which the pivotal axes of said wall portions occupy a position parallel to the initial position of said axes, and means operatively connected to said wall portions for rotating the wall portions about said spindle axes whereby the flow area through said nozzle is varied.

6. A discharge nozzle for -a propulsive fluid stream comprising a duct for conducting the fluid stream, said duct having upstream and downstream ends, a pair of oppositely disposed generally semicircular wall portions adjacent the downstream ends of said duct, a casing surrounding said duct and wall portions, supporting means for said wall portions, means pivotally mounting the upstream ends of said wall portions on said supporting means about an axis transverse to the fluid flow, means operatively connected to said mounting means for moving the same to a position in which the pivotal axes of said wall portions occupy a position parallel to the initial position of said axes, first and second spindles protruding from the same sides of said wall portions and in spaced alignment With each other, yokes rotatably mounted on each of said first and second spindles, piston rods connected to both ends of each of said yokes and extending toward each other, a common cylinder block positioned between said yokes and receiving the ends of said piston rods, means slidably connecting said cylinder block to said casing, said cylinder block being slidable in an upstream and downstream direction, pistons fixed to each of the ends of said piston rods, and means operatively associated with said cylinder for actuating said pistons to thereby rotate said wall portions to vary the flow area through said nozzle.

7. A discharge nozzle for a propulsive fluid stream comprising a duct for conducting the .fluid stream, said duct having upstream and downstream ends, a pair of oppositely disposed generally semicircular wall portions adjacent the downstream end of said duct, a casing surrounding said duct and wall portions, sleeves secured to the upstream ends of said wall portions, first and second spindles passing through said sleeves and extending transversely to the fluid flow to pivotally mount said wall portions about said spindle axes, means operatively connected to said spindles for moving the same to a position in which the pivotal axes of said wall portions occupy a position parallel to the initial position of said axes, third and fourth spindles protruding from the same side of said wall portions and in spaced vertical alignment with each other, yokes rotatably mounted on each of said third and fourth spindles, piston rods connected to both ends of each ofsaid yokes and extending toward each other, a common cylinder block positioned between said yokes and receiving the ends of said piston rods, means slidably connecting said cylinder block to said casing, said cylinder block being slidable in an upstream and downstream direction, pistons fixed to each of the ends of said piston rods, and means operatively associated with said cylinder block for operating said pistons to thereby rotate said wall portions to vary the flow area through said nozzle.

8. The combination set forth in claim 7 and further comprising sealing means between the upstream ends of said wall portions and said duct, said sealing means being yieldable to accommodate relative movement between said wall portion and aid duct.

9. The combination set forth in claim 8 wherein said sealing means comprises a plurality of flexible fingers and circumferential extensions overlapping adjacent fingers.

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